Hi,
You are right APD(http://kb.vmware.com/kb/1016626) condition wont trigger as long the last avaialble path is active.
"Could not connect via the vSphere client and the DCUI was unresponsive once you authenticated. VMs also froze, but could still ping" .It's pretty clear that hostd agent was hung!! At times i have seen DCUI also freezing out which happened in this case .I believe you have rebooted the host to recover from the scenario.Is there a chance where in you can check or upload the logs? If there are no dead paths most likely you will see SCSI reservation errors which will certainly freeze the hostd agent.